We have an HP Compaq dc7900 in the office. 4 days ago it had several problems in the USB connection; that we couldn't connect anything via any USB port (tried a scanner and a walkman). We left the problem unsolved (and undiagnosed) and went to vacation, and when returned today, and when attempted to power it on, the PC starts booting and before it gets anywhere it just freezes (effectively hangs if I may say so), with the screen showing the following text:

The keyboard at this point isn't responding. When rebooting (a hard reboot) the same thing happens over and over, but I notice that the keyboad responds within the first few seconds after that screen of hang appears (2 or 3 seconds) and pressing F9 or F10 triggers the option but leads nowhere (still hangs). I've been able to take the hard disk and back it up somewhere else, but regarding the PC I have no idea or a clue to start with, as I can't think of a cause of the problem.

What can be this problem? And what steps can I take to further diagnose and resolve the problem? Any guidelines and direction of research are thankfully welcomed...

EDIT: I'd like to apologize to those who answered and/or reviewed this question. I was not able to follow up and update the question as my company took the CPU to the repair shop and the repair shop took it to another one that is unreachable to me. The last person I could follow up with said that he suspects the problem to be a hardware problem, exactly in the I/O chip on the motherboard, but with no further details. I will follow up whenever I could find any more details or when the repair shop returns the CPU (if it was not replaced). I hereby want to say sorry for every contributor in this post, and for the community for not completing and following up with the question. Thank you all.

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1

This sounds like silent boot is enabled, please have a look at your BIOS and disable silent boot if possible. If that works, the initial bootscreen may provide additional information about what the computer does while it 'hangs'.
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Michael KJan 2 '12 at 13:44

Did all the above. Nothing changed. What are you suspecting of?
–
amyassinJan 2 '12 at 13:03

1

It helps me sometimes to get the system working again. Have you changed something in the bios before the vacation when trying to get the usb working? Some HP PCs can go to repair/recover menu by pressing F4 when powering on.
–
ott--Jan 2 '12 at 14:25